1. Field of the Invention
The present invention relates to compositions of diamond and non-diamond particulate solid materials consolidated with polycrystalline diamond, and to methods for manufacturing these materials.
2. The Prior Art
The advent of methods for formation of polycrystalline diamond films has opened up a wide variety of new applications for diamond as an engineering material. Thin (.apprxeq.4000 .ANG.) films of this new material have become the basis for commercially available X-ray detector windows (sold By Crystallume of Menlo Park Calif.), while thicker diamond films (typically 0.3-0.5 mm) are being used to enhance the power dissipation capabilities of thermally-limited electronic devices such as laser diodes, laser diode arrays, and microwave power amplifier transistors.
While solid diamond films, produced by chemical vapor deposition methods, are finding increasing commercial utility, cost is still a barrier to their radiation into wider use. In particular, for applications which require very thick sections and/or which require fabrication of complex shapes, the polycrystalline CVD diamond materials are often prohibitively expensive, due to the excessive deposition time required to grow thick sections, and/or due to the extreme expense of mechanically fabricating diamond, the hardest known substance.
Earlier attempts at consolidation of diamond particles using diamond CVD are known in the art. The earliest known of these were experiments by William G. Eversole, which consisted of passage of methane gas over heated diamond dust. These experiments, which led to an issued U.S. Pat. No. 3,030,188, produced only a thin, hard, mainly graphitic crust of deposited material on the exterior of the diamond powder mass, leaving the interior unconsolidated.
Other later attempts by Japanese researchers involving pyrolysis of methane and/or benzene on heated diamond dust led essentially to the same nonutilitarian results achieved by Eversole, and did not demonstrate a useful degree of consolidation of particles (Matsumoto, S; and Setaka, N; Consolidation of Diamond Powders by Thermal Decomposition of Methane and Benzene; Journal of Materials Science, vol. 15, pp. 1333-1336).
The lack of success in these attempts at consolidation of particulates by formation of a matrix of diamond material stimulated development of alternate technologies, including use of "glues" (such as liquid metals) which are infiltrated into the particulate mass liquid form and allowed to solidify through freezing and shock-consolidation methods, in which explosively generated shock waves pass through a diamond particulate mass and briefly melt the diamond particles, with solidification and partial consolidation occurring after passage of the shock wave (Potter, David K.; Ahrens, Thomas, J.; Dynamic Consolidation of Diamond Powder into Polycrystalline Diamond, Applied Physics Letters 51 (5), Aug. 3, 1987, pp. 317-319). This technology has not been capable of producing commercially useful diamond composite or consolidated objects due to its inability to generate large pieces (e.g., volumes.gtoreq..about.1 cm.sup.3) without cracks and other structural flaws.